The present invention relates to a motor device and a wiper apparatus. The motor device is provided with a motor portion which can be rotated forward and in reverse, and a link mechanism coupled drivingly to the motor portion. The link mechanism is integrally assembled in the motor portion. The wiper apparatus is provided with the motor device and a wiper control circuit controlling the motor device.
A motor device disclosed in Japanese Laid-Open Patent Publication No. 11-34805 is used as a wiper motor reciprocating a vehicle wiper. A link mechanism compensate for a lack of torque.
In the case that the link mechanism is not provided, and an output shaft of the wiper motor is directly connected to the wiper to reciprocate the wiper, a positional accuracy of the wiper may deteriorate in the case that the wiper is positioned at an upper reverse position and in the case that the wiper is positioned at a lower reverse position. This is because the wiping force and the wiping speed of the wiper directly depend on a predetermined drive torque and rotation speed of the wiper motor. That is, the lack of torque of the wiper motor may be generated near the lower reverse position and the upper reverse position, where a relatively great wiping force is needed to operate the wiper. The lower reverse position of the wiper also serves as a stop position of the wiper.
However, the link mechanism of the publication mentioned above transmits a rotating motion output by the motor portion to the wiper while converting the rotating motion into reciprocation such that a higher torque is generated at the upper reverse position and the lower reverse position of the wiper. Accordingly, the positional accuracy of the wiper is improved at the lower reverse position and the upper reverse position, and the lack of torque is compensated for. In other words, the link mechanism complements the output characteristic of the motor portion.
There is a tendency that a mounting space of the wiper apparatus to a vehicle is limited more and more. Accordingly, there is a demand for an adjustment of a layout of constituting parts of the wiper motor so as to downsize the wiper motor serving as a driving source of the wiper apparatus.